Composite items are generally constructed from multiple layers that may be laminated together. These composite layers may be referred to as partial or full plies. For items having dimensions exceeding the available width of the material used to form the composite layers, each layer is typically formed from a series of strips or courses of the material. These strips or courses may be placed next to each other, such as in an edge to edge configuration or having some overlap. The material used for composite items may be woven fiber fabrics, unidirectional fiber materials (e.g., tapes), metal foils, adhesive films, and a variety of other conformations. The fibers may be made from natural and/or man-made materials, such as fiberglass, graphite, and the like.
The strips or courses are generally laid based a specific pattern or configuration to form each composite layers. Deviations from this pattern may result in wrinkles, twist, gaps, overlaps or, more generally height variations, which may be referred to as anomalies. Other types of anomalies include foreign objects, such as bits of backing material, debris, and blobs, which may appear on the surface of a composite layer as the layer is being formed. It is desirable for these anomalies to be identified and corrected prior to placement of the next layer.
Inspection of such composite layers for anomalies can be performed manually with human technicians or with conventional machine vision systems. Manual inspection may increase fabrication time and expense. Conventional machine vision systems may be implemented to increase the overall production rate and minimize human errors. Both of these inspection approaches typically inspect only one layer at a time and provide information about anomalies in currently inspected layer. Other layers disposed under the currently inspected layer may not be considered when determining a course of action.